text: Position of n among the numbers made of 2 , 3 , 5 & 7 |  ; If number is 2 then it is on the position pos * 2 + 1 ; If number is 3 then it is on the position pos * 2 + 2 ; If number is 5 then it is on the position pos * 2 + 3 ; If number is 7 then it is on the position pos * 2 + 4 ; Driver code
code: #include <algorithm> NEW_LINE #include <iostream> NEW_LINE using namespace std ; int findpos ( string n ) { int pos = 0 ; for ( int i = 0 ; n [ i ] != ' \0' ; i ++ ) { switch ( n [ i ] ) { case '2' : pos = pos * 4 + 1 ; break ; case '3' : pos = pos * 4 + 2 ; break ; case '5' : pos = pos * 4 + 3 ; break ; case '7' : pos = pos * 4 + 4 ; break ; } } return pos ; } int main ( ) { string n = "777" ; cout << findpos ( n ) ; }